This document provides technical information for fabricating KOMADUR Type 1 PVC sheets. It discusses that KOMADUR sheets can be easily machined, formed, welded, and bonded. The document then provides details on machining techniques like sawing, drilling, turning, and milling. It also discusses forming techniques like folding, bending, and thermoforming. Guidelines for cutting speeds and tooling are provided for different fabrication processes.

1. TECHNICAL INFORMATION AND FABRICATION
KOMADUR WA PVC-U TYPE 1
Flame Retardant & Resistant to Chemicals
KOMADUR is a Type I PVC sheet that meets the most specific demands for the
chemical,
building and
electrical engineering industries.
From the point of view of users, KOMADUR PVC Type I is easy-to-use and offers a very high level of
efficiency when fabricated.
KOMADUR is the result of intensive research and development work as well as more than 30 years’
experience in the extrusion of PVC sheets. During this period, the material has undergone continuous
development and improvement and been adapted to suit the changing needs of the market. The result is a
system of solid Type 1 PVC sheets that stand out, thanks to their homogeneous, smooth and glossy
surface finish. They are flame-retardant, and resistant to chemicals and corrosion, in line with DIN
8061, as well as to most aggressive environments.

2. KOMADUR PVC Type I is exceedingly easy to work. It can be cut, sawed, turned, filed,
drilled, planed, milled, ground, welded and screwed. It can also be formed in many
ways, including stretch forming, thermoforming, vacuum forming, blow molding,
bending, punching.

4. There are no toxic or harmful substances in KOMADUR that can be given off over
the long term. KOMADUR is free from formaldehyde, asbestos, lindane, PCB, PCP and
CFCs. What’s more, it is cadmium and lead‐free and is also made without any monomers,
biocides and plasticisers.
KOMADUR poses absolutely no hazard to people or the environment, neither during its
manufacture, while in use, or during the recycling process. Old sheets no longer in use or
left‐over sections of sheets can be recycled without any problem: they are ground up in
shredders and cutting machines before being returned to the production process to make
new sheets. This closed material cycle is not only economical, but ecological, too.
Certified to DIN ISO 9001 ‐ “Uncompromising quality from start to finish”
Systematic research and development work and decades of experience with plastics are
the basis for the generally recognized high quality of our products. We carry out tests at
all stages – starting with the raw materials on delivery through to final inspection of the
finished products.
Regular examinations and analyses conducted by independent testing institutes confirm the high
degree of care we take during the production process. Our quality assurance system is certified to
DIN ISO 9001.
Fabrication
The information below provides further direction for fabricating KOMADUR.

5. • Machining
• Working process/Cutting geometry
• Forming (non‐cutting shaping)
• Welding
• Bonding
Fabrication: Machining
When working with KOMADUR PVC sheets, there are a number of special guidelines and
directions that must be complied with. The following data and values are provided for
orientation purposes. Although they have been obtained by conducting a great variety of
trials and tests, they cannot be assumed to be binding for every type of application.
Almost all tools and machine tools used to work metal and wood can also be used
to work KOMADUR PVC sheets. The cutting speeds are high, the feed rate low and the
cutting depth also low. In most cases, there is no need to cool either the cutting tools or
the cuts themselves, provided that the cutting edges of the tools are kept sharp and the
heat that arises through the cutting process is dissipated by quickly removing the chips. If
the depth of the cut is deeper, the cut will have to be cooled in order to prevent the
material from “smearing”: this can be done using compressed air or water (cooling
medium).
Furthermore, the existing safety instructions also require that chips and dust be properly
extracted.
Please note that whichever method is chosen to work KOMADUR, deep grooves and
sharp edges must be avoided as they would lead to early breakage of the material due to
the known notching effect when put under strain. Smooth surfaces at the edges can be

6. obtained by finishing them with buffing wheels made of felt, unbleached calico or sisal
weave, or with felt tapes. Grinding or polishing pastes can also be used. Uneven edges
that arise during sawing, drilling or milling can be given a clean finish using flat scrapers
(grinding angle 15°).
Guideline values regarding the cutting conditions and shapes of cuts and sections in
connection with the working processes described below can be found in the table on page
15; for further details, see VDI Specification 2003.
Sawing
High‐speed band saws and circular saws with a cutting speed of up to 3,000 m/min are
recommended. Depending on the thickness of the sheets, saw blades with a tooth pitch of
between 5 and 10 mm are used. For circular saws, it is normally recommended to use
blades with a tooth geometry that alternates between flat teeth, trapezoidal teeth and
carbide‐tipped teeth.
The saw blade diameter (Ø) and the number of teeth (t) must be coordinated to match
the material to be machined, the machine type and the machine speed.
In order to obtain clean edges to cuts and to avoid cracking, always clamp the sheet
material in the work‐holding fixture in such a way that it does not vibrate. This is
especially important for thin sheets with a thickness of 1‐3 mm, not only when machining
them singly, but also in a stack. Use guillotine shears to cut a thickness of 1 mm.
In the case of jigsaws, use only sharpened, unset saw blades (plastics, PVC). The feed
(manual) must be at a slow, constant speed. In particular cases, it may be advisable to
make use of the consulting service offered by the saw‐blade manufacturer.
Information about the cutting geometry of the machining processes can be found in the
Working process/Cutting geometry table. The information and instructions given by the
respective machine manufacturer must of course be observed.
Drilling
All PVC sheets in question can be drilled using the sort of twist drills familiar from
drilling metals (DIN 1412 twist drills) whose angle of twist is approx. 30°. The point (or
nose) angle can be up to approx. 110°, while the lip relief angle should be no smaller than
12‐16°.
The cutting and feed speeds depend on the depth of the hole to be drilled: the thicker the
sheet, the slower the speed.
For holes larger than 20 mm in diameter, two‐flute cutters with pilots are used. Holes
larger than 40 mm in diameter are cut using circular cutters (e.g. quick‐ helix drills).

7. Turning
When rough turning, it is advisable to combine a slow feed rate with a greater cutting
depth and to use a cutting tip with a radius of at least 0.5 mm in order to obtain a groove‐
free surface.
The cutting depth should be maximum 2 mm for fine turning. If a faster feed rate is
selected, cracking of the material can be avoided by setting a slower cutting speed.
Milling
The milling tools have to be ground so that they are suitable for working the plastic
material. They must also provide enough space for an adequate volume of chips. Working
with a fast forward feed rate along with moderate cutting speed and deep cuts will lead to
good results. 3‐D milling can also be performed without any problem with KOMADUR.
For this purpose, the plotter system is equipped with a special ball nose end mill and
linked with suitable computer software.
Cutting, punching, perforating
KOMADUR sheets up to 3 mm thick can be cut with guillotine (sheet) shears. The cut
must be made swiftly and without interruption. The sheets should have room
temperature, i.e. at least 20 °C. Thicker sheets (> 3 mm) should be cut using a saw.
KOMADUR sheets up to 3 mm thick can be punched and perforated with profiling knives
or two‐piece tools. Also recommended are punching tools (made of strip steel) with facet
cut (beveled edge) on both sides. Heating the PVC material to 30 to 40 °C is useful and
aids the working process.
Laser Cutting
Due to the heat that is transferred to the material during laser cutting, this process is
unsuitable for rigid foam sheets.
Water‐jet cutting
An alternative cutting technology (cold‐cutting process) is water‐jet cutting.
This cutting method is especially suitable for KOMADUR when complex contours are to
be cut out.
Up to a sheet thickness of 3 mm, cutting can be performed using a pure water jet. For
thicknesses of 4 mm and more, however, an abrasive agent (e.g. silica sand) should be
added to the cutting water.
Different cutting speeds can be used depending on the type and thickness of the sheet
and the type and quality of the cutting unit. The cutting speed depends mainly on the
quality of the cutting surface wanted and should perhaps be discussed and agreed upon
with the customer.

8. At the beginning of every series, therefore, we advise you to first of all determine the
correct cutting speed with respect to the quality of the cutting surface.
Working process/Cutting geometry table

9. Fabrication: Forming (non‐cutting shaping)
KOMADUR PVC sheets can be formed, (i.e. worked or shaped without cutting), by
means of a number of different processes: folding, bending, compression molding,
upsetting, stretch forming and thermoforming.
The accompanying diagram shows that the forming properties of KOMADUR PVC sheets
are dependent on the temperature. These properties are of practical importance with
regard to workability and use of the sheets.
The modulus of elasticity and the tensile strength indicate the deformation resistance,
the elongation at tear, and the deformability of the material at the respective
temperature. Usually, the sheets are formed during the elastic‐plastic phase of the
material, in which maximum degrees of expansion/elongation are reached and the forces
required for forming can be kept low.

10. In order to prevent damage to their structure, KOMADUR sheets must not be formed at
and below the softening temperature, (i.e. at temperatures below 90 °C). The most
favorable temperature range for each of the various hot‐working processes depends on
the sheet material and application (120‐140° C for folding, bending, compression molding
and thermoforming; 135‐180° C with restrictions). If the material is heated above 180° C, it
initially leads to discoloration and then to thermal damage. Avoid forming rigid foam
sheets at temperatures below 120° C to avoid damaging the cell structure.
Good forming is possible only when the sheet material is thoroughly and homogeneously
heated. The sheets are preferably heated using infrared heaters, but heating ovens or
circulating‐air ovens can also be used. During folding processes, for example, the sheets
require localized heating, for which heating elements can be used.
Furthermore, we recommend sheets 3 mm thick and more be heated on both sides in
order to avoid damage to the one surface through overheating and to shorten the heating
time.
Thermoforming and stretch forming
KOMADUR PVC sheets can be thermoformed or stretch‐formed on all commercially
available forming machines. The only stipulation is that the machines are protected
against draughts on all sides.
Fast working cycle times can be achieved if the tools used for these forming processes are
cooled. In the case of vacuum forming, sand blasted surfaces have the advantage that the
air can be completely extracted without leaving any air pockets. The diameter of the
vacuum bores should not exceed 0.8 mm in order to prevent deformation of the drill
holes. The edges should generally be rounded with a radius that is no more than between
one and three times the thickness of the sheet.
In the case of KOMADUR, male molds must be sufficiently conical: approx. 5°. Female
molds do not need to be conical, as the thermoformed parts separate from the mold as
they cool down.
Cooling is generally carried out using compressed air. Compressed air combined with
sprayed water, however, must not be used until the surfaces have hardened.
Of the various thermo and stretch‐forming processes, particular mention should be made
of the air‐slip processes in which the heated sheets are pre‐stretched pneumatically, (i.e.
by air). These processes are the ones that generally produce thermoformed parts with the
most uniform material thickness.
In this connection, it is important to mention that the forming process of the material
stops wherever the PVC sheet touches something (the mold).

11. Thermoformed parts will for the most part not warp if the forming temperature is high,
the parts are cooled down slowly, the molds are opened at rather low temperatures, and
the rims are trimmed immediately after the parts have been removed from the molds. For
the forming process itself and the design of the molds, the shrinkage of sheets has to be
taken into account. KOMADUR sheets can shrink by up to 0.5%, particularly in the
direction of extrusion.
Folding, bending, compression molding
Folding and bending of KOMADUR PVC sheets must only be performed on suitable
equipment. The bending radius must never be smaller than two to three times the
thickness of the sheet. The heated zone should have a width of at least five times the
thickness of the sheet.
After cooling, linear heating of the material will lead to stresses developing within the
PVC, which cause warping when folding short lengths.
Sides with a length 20 times the thickness of the sheet will not warp. For this reason, we
recommend you heat up the entire section in order to prevent short sides from warping.
Folds with a relatively small radius can be made by notching (V‐notch) the inner side.
Hot‐folding of sheets
To prevent the cell structure from being stretched to too great a degree, a minimum
bending radius of approximately twice the thickness of the sheet must be observed. In the
case of PVC sheets 8 mm or thicker, please remove the excess material by milling a V‐
shaped groove along the inside of the bending edge before bending.
You can then carefully heat up the outside of the bending edge, bend up a fold and bond
the joint created. However, a remaining thickness of 1 to 2 mm must be left in the rigid
foam sheets. When milling, make sure that the V‐shaped groove is 1° larger than the
desired bending angle, i.e. 91° in the case of a 90° angle.
Cold‐bending of sheets
The minimum bending radius when cold‐bending rigid foam sheets is roughly 100 times
the thickness of the sheet (i.e. 200 mm for a 2 mm‐thick sheet). To cold bend thick
sheets, use a bench saw to saw around ten parallel grooves into the sheet with a clearance
between them the width of the saw blade, leaving a remaining thickness of 1 to 2 mm. You
can also use this method to bend thick sheets to any desired angle without heating them.
Embossing
Impressions such as letters, characters, numbers and ciphers are embossed with tools
familiar from sheet‐metal working and the cardboard and leather industries. The tools
must be preheated (100–130 °C are recommended).

12. The actual embossing process generally does not require the sheet material to be heated.
Further information and useful advice on forming PVC‐U sheets can be found in VDI
specification 2008, pages 1 to 3.
Hot‐working processes
In order to prevent damage to their structure, KOMADUR sheets must not be formed at
and below the softening temperature, (i.e. at temperatures below 90 °C). The most
favorable temperature range for each of the various hot‐working processes depends on
the sheet material and application (120‐140° C for folding, bending, compression molding
and thermoforming; 135‐180° C with restrictions). If the material is heated above 180° C, it
initially leads to discoloration and then to thermal damage. Avoid forming rigid foam
sheets at temperatures below 120° C to avoid damaging the cell structure.
Fabrication: Welding
KOMADUR is made of thermoplastic materials. The sheets can be welded by means of
familiar welding processes, such as hot‐gas welding, heated‐tool welding, folding and
welding and friction welding, and using all pieces of equipment commonly available on
the market.
Please always make sure before welding that the sheets in the welding zone have been
properly cleaned with a cleaning agent or, better still, by machining.
After the welding process, and depending upon the kind of product and application, you
have to decide whether the weld seams need finishing or not. Filing, planing, grinding or
smoothing are suitable methods to finish the weld seams. In all cases, it is important to
work with care in order to avoid notching.
Hot‐gas welding (with welding rod)
When hot‐gas welding with a welding tip, the sheet material and the welding rod are
plasticised at the weld by means of heated gas (max. 0.3 bar, low‐ pressure blowers, e.g.
from Leister, Wegener, Zinser, Forsthoff) and preferably oil and water‐free compressed
air, and are then joined under pressure.
The necessary welding rods are part of our production range; they are available as coils or
as pieces in different lengths and with different profiles. Both manual welding and
machine welding are possible. The market offers a wide range of different welding
equipment and welding tips.
In particular, high‐speed nozzles have proven themselves, enabling high welding speeds
and producing good and reliable weld seams by evenly heating up the sheet and welding
rod.

13. Semi‐automatic welding units with mechanical feed are particularly suitable for series
production runs.
The most frequent welds are the fillet weld, the single V and the double‐V butt weld (see
DIN 16930 and 16932). Thin sheets are joined by single‐V butt welds, thick sheets by
double‐V butt welds. The latter should be produced by welding on both sides, alternately,
to avoid warping and buckling. The standard values for the temperature of heated gas
(measured in the nozzle) as shown in the accompanying table should be complied with in
order to achieve weld seams with good welding factors.
Heated‐tool welding (butt welding)
Another method of welding KOMADUR PVC sheets is the heated‐tool welding
procedure, in which tools of different shapes (circular, sword‐shaped) are used. The
perfectly smoothed‐out and cleaned surfaces of the parts to be welded are heated up
slightly by pressing them against the heated tool until they are plasticised. They are then
pressed together.
This welding process is simple and time saving, and produces joints that are almost free
of stress and capable of withstanding high stress.

14. As long as the welding conditions, which depend on the material (temperature of the
heated tools, contact pressure against the tool, contact pressure when joining and
immediate joining after plasticising), are adhered to, the strength of the welding seams is
almost equal to the strength of the basic material itself. Please refer to the above chart for
these heating and contact‐pressure conditions.
Welding
The following parameters must be precisely adjusted and checked at regular intervals.
During the course of heating, the plasticised material forms a bead. Heating should be
stopped when this bead is 1‐2 mm thick. The contact pressure of the heated tool against
the sheet must be set so low in order to avoid too much of the plasticised material being
squeezed out of the plasticised zone.
Immediately after removing the heated tool from the sheet, the plasticised parts must be
firmly pressed together until the material has hardened again.
Folding and welding
The folding and welding process is a modification of the butt‐welding process. The sheet
is resting on an even surface. The heated tool is placed on the sheet along the bending
(folding) line as a cutting edge until it melts into the material.
The edge of the bar has an angle of 60° for rectangular folding. The bar should penetrate
the sheet by up to 2/3 of its thickness, before it is raised again. Immediately on removing
the bar, the sheet is folded and welded along the plasticised line.
In order to produce the necessary pressure at the heated bar, the angle between the edges
to be welded must be 15° to 20° smaller than the folding angle wanted. If thick sheets have
to be folded, the heating time can be reduced by milling a wedge‐shaped groove into the
welding line before applying the heated bar.
Fabrication: Bonding
KOMADUR sheets can be bonded to one another, and to other materials. Different
adhesive types may be used depending on the requirements and the specific use. Though
several other adhesives can be used, we recommend bonding KOMADUR sheets together,
and to other substrates, using KORAFIT. We also suggest testing any adhesive prior to
using it in a production situation. The stability characteristics of the cured bonding seams
lie within the material stability range of the sheets themselves.